Hydraulic differential control mechanism



Nov. 1, 1955 F. A. CABELL HYDRAULIC DIFFERENTIAL CONTROL MECHANISM 4 Sheets-Sheet 1 Filed May 28, 1952 W 73. fi-

Fora/(er A. Gabe/l INVENTOR.

Nov. 1, 1955 F. A. CABELL 2,722,134

HYDRAULIC DIFFERENTIAL CONTROL MECHANISM Filed y 28, 1952 4 Sheets-Sheet 2 v.9 T 98 m8 mm mvk mi N is W Fara/rer A. Gabe/l INVENTOR.

BY 2mm.

Nov. 1, 1955 F. A. CABELL 2,722,134

HYDRAULIC DIFFERENTIAL CONTROL MECHANISM Filed May 28, 1952 4 SheetsvSheet 5 i I I I I I I I l I I I l I l I I3 g g l v i H Foraker A. Gabe/l if INVENTOR. l l L- J F. A. CABELL 4 Sheets-Sheet 4 Forakar A, Gabe/l INVENTOR.

8) Ammqs Nov. 1, 1955 HYDRAULIC DIFFERENTIAL CONTROL MECHANISM Filed May 28, 1952 United States Patent O HYDRAULIC DIFFERENTIAL CONTROL MECHANISM" Foraker A.- Cahell; Nashville; Tenn;

Application May 28,- .1952, .Serial N 0. 290,552

16 Claims; (Cl; 74-472) This invention'relatesto improvements in the conventional vehicle differentialz This conventional differential consists substantially of an arrangement of gearwheels, forming an epicyclic gear train'whichconnects to rear axles in the same straight line soastoact a-s an ordinary coupling under normal-conditions. However; this coupling is able to divide driving forcesequally between the axles and at the same time permit one axle to revolvefaster than the other axle, and to allow driven wheels associated with the axles to make equal useofan idling motors retarding force. In performingthese'necessary functions the conventional differential may; under slippery road conditions, actually become an important" factorin preventing a motor'of a-vehiclefor movingthesame along'a road. Slippery road conditions cause conventionaldiiferentia'ls to-allow' a driven wheel obtaining the smaller amount of traction of the two wheels Withrespectto the road to slip over the roadsurface while-the driven wheel'obtainingthe greater-amount of traction remains relatively stationary; and thus'makes'an-ineifectuahcontrihution towards movement'of the vehicleover' the'road. It is, therefore, logical toassume that a-verypotent forward'or backward'thrust' couldbe'imparted toa vehicle if'a practical way'were found for selectively coupling, at the willof an operator of thevehicle, theslipping wheel with the relatively stationary wheel, andforautomatically uncoupling these wheels asthe'need arises.

The primary object of this invention is to provide a hydraulic differential control mechanism for permitting regulated differential action. of a rear axle differential assembly as well'as unregulated differential action thereof.

Another object of this invention is to. provide means for permitting regulated differential action of'the rear: axle differential assembly at the will'of the. vehicles operator as Wellas anunregulated differential action.

Another object of this invention is to provide an improved rear axle differential assembly which isprovided with a hydraulic differential control mechanism, said control mechanismbeing capable of automatically, as the needarises, to change the action-of" the rear axle differential assembly from unregulated differential actionto'regulate'd differential action; or from' regulated differential action to unregulated diiferential action.

Another object of thisinvention is to provide an-improved-hydraulic differential control mechanism for selectively'eliminating-differential action of 'arear axle differential assembly whereby a more effieient driveunit for' a vehicle may be realized, said modified rear axle differential assembly utilizingmany parts ofconventional differential units to effect 'a maximum economyand manufacture;

A furtherobject of this inventionlisto providean improved hydraulic differential. control mechanism for rear axle differential assemblie.s,. said' control mechanism adaptedlto regulate the diiferentialaction-of'the differential assembly automatically whenever an operator of a vehicle soxequipped actuates anaccelerator pedal? of the vehiclei ice A still further-object; of this invention: is: to provide an improved hydraulic differential control mechanism: for a rear axle I differential assembly, said control mechanism being providedwith facilities for continuously and automatically averting. strain to parts thereof which would result from sudden:.failure':of a vehicles tire'onzadriven wheel, or the imposition: of any operatingzcondition on the vehicle which would place practically allzof'its motors torque on one-general wheel; while the-controlmechanism was inlthe act of: regulating differentialaction-thereof;

With these objects definitely in view, this invention: resides in certain. novel featuresofi construction; combination andarrangement of elementstandtportions as will be hereinafter described-in detail in thespecification", particularly pointedout in the:appended claims, andillustrated'in theaccompanying drawings which forrn' a material part' ofthis application and in -which:

Figure 1 is a schematic side'elevational-viewof a floor portion ofa vehicle'in which arear axle differential assembly of the vehicle is equipped with the hydraulic dif ferential control mechanism which is the subject of this invention, also shown is the means associated with an accelerator pedal of the vehicle for actuating the control mechanism;

Figure 2 is an enlarged longitudinal vertical sectional view taken through the center of the means for actuating the control mechanism and showing the same in an inoperative position whereby the. same cannot be actuated by the accelerator pedal;

Figure 3 is an'enlarged longitudinal vertical sectional view taken through the rear axle assembly illustrated in Figure 1 and shows the general construction thereof, a differential carrier thereof being provided with an actuating pump assembly, said actuating pump assemblybeing illustrated in an operative position; i

Figure 4 is a fragmentarylbngitudinalvertical sectional view'similar to'Figure 3 and shows the means for moving a'pistonof the actuating pump assembly from anoperative position to an inoperative position, said means being in an inoperative position;

Figure 5 is an enlarged fragmentary longitudinal'horizontal sectional view taken through the center of the rear axle assembly of Figure l and shows the general construction of the interior thereof including the interiorof a.dif ferential assembly;

Figure 6 is a transverse vertical sectional view taken substantially upon the. plane indicated by the sectionline 6'6 of Figure 3 and shows the general construction, of the actuating pump assembly;

Figure 7 is a transverse vertical sectional view taken substantially upon the plane indicated by the section. line 77' of Figure 3 and shows the general: construction of. a differential pump assembly mounted within a differential gear. case androperatively connectedto the. actuating pump assembly of the differential carrier;

FigureSis a fragmentary transverse vertical sectional view similar to Figure 7 and showsthe relationship: of of cylinders ofthe differential pump assembly in expandedpositions'; and

Figure 9 is aschematic diagram showingthearrangement of fluid passages for connecting said' differential pump assembly to the actuatingrpurnp assemblyt.

Similar characters of reference designate similar or identical elements and portions throughout therspecification and throughout' the different views ofthe. drawings.

Referring now to the drawings in detail,.it willibe seen that. there isillustrated a rear axle assembly for acon ventional vehicle, said rear axle assembly. including. a rear axle gear case, which is referred: toin general by the reference numeral 10. The. rear axle. gear case 10 includes a differential carrier housing 12 mountedlatithe forward end thereof and secured thereto by a plurality of bolts 14. The differential carrier 12 includes a pair of longitudinally spaced transversely extending portions 16 and 18 in which are mounted front and rear drive pinion shaft bearings 20 and 22, respectively. Mounted within the bearings 20 and 22 for rotation is a drive pinion shaft 24, the drive pinion shaft 24 being adapted to be connected to a motor (not shown) of a vehicle and rotated thereby. The rear end of the drive pinion shaft 24 has integral therewith a drive pinion 26.

Referring now to Figure in particular, it will be seen that mounted within the rear axle gear case is a conventional differential gear case 28 which has secured thereto a ring gear 30, the ring gear being in engagement with the pinion 26 and driven by the same. It will be understood that the differential gear case 28 is of a conventional construction and includes a pair of halves, not shown in detail, which are secured together by fasteners (not shown), and that the means securing together the halves of the differential gear case 28 may secure the ring gear 30 thereto if the same is formed separate of the associated half of the differential gear case 23.

The differential gear case 28 and the associated ring gear 30 are mounted within the rear axle gear case 10 for rotation and are supported by hearings on opposite sides thereof. It will be understood that the bearings include a first bearing assembly 32 which is carried at the left side of the rear axle gear case 10, as viewed in Figure 5, by a differential bearing cup 36 secured to the rear axle gear case 10, in any conventional manner. The right side of the differential gear case 28 is supported by a bearing assembly 34 which includes a special differential bearing cup 38, the differential bearing cup 38 being supported by the right side of the rear axle gear case 10.

Mounted within the differential gear case 28 is a differential pinion shaft 40 which is shown as substantially in alignment with the drive pinion shaft 24. The differential pinion shaft 40 is journaled within bores 42 in the ends of the differential gear case 28 for rotation with respect to the same and has formed integrally with a forward end portion thereof a first differential pinion 44. Mounted on the difierential pinion shaft 45 adjacent the rear bore 42 is a second differential pinion 46, the differential pinion 46 being free to rotate with respect to the differential pinion shaft 40. Also mounted within the differential gear case 28 for rotation therewithin are a pair of side gears 48 which are in engagement with the differential pinions 44 and 46 and are adapted to drive the same. The differential gear case 28 is provided with a pair of opposed longitudinally extending bores 50 in which are mounted axles 52, the inner ends of the axles 52 being provided with splined connections 54 with their respective side gears or axle pinions 48.

It will be understood that during the normal operation of the rear axle assembly rotative force is transmitted to the drive pinion shaft 24 with the resultant rotation of the drive pinion 26. Inasmuch as the ring gear 30 is in engagement with the drive pinion 26, the same is also rotated and results in the rotation of the differential gear case 28 to which it is attached. During the normal operation of a vehicle, the differential gear case 28 and its associated gears and the axles 52 rotate as a unit. However, when wheels (not shown) attach to the axles 52 go around a curve or one of the wheels slip, one of the axles 52 turns faster than the other axle 52 whereby a direct connection between the axles 52 no longer exists. The relative rotation of one of the axles 52 with respect to the other axle results in the rotation of the side gears 48 and the associated pinions 44 and 46. This particular action is well-known as a differential action, and while it is desirable in the case of driving vehicles around curves, having tire blow-outs, etc., it will be seen that it has a disadvantage in that a car may be easily stuck in that slippage of one wheel only prevents the driving of the vehicle. It is, therefore, desired to provide means 01 selectively locking the differential pinions 44 and 46 against rotation whereby the differential action may be controlled, and in order to perform this function there has been provided the hydraulic differential control mechanism, which is the subject of this invention.

Referring now to Figures 3 and 5 in particular, it will be seen that formed between the transversely extending portions 16 and 18 of the differential carrier 12 is an actuating pump assembly, which is referred to in general by the reference numeral 56. The actuating pump assembly 56 includes a vertically extending cylinder 58 formed in the casting which is the major portion of the differential carrier 12, the cylinder 58 being positioned between the transversely extending portions 16 and 18 and opening through the upper surface of the differential carrier 12. The upper end of the cylinder 58 is closed by a cover plate 60 which is secured to the differential carrier 12 by a plurality of fasteners 62, the closure plate 60 being flush with the upper surface of the differential carrier 12.

Mounted within the cylinder 58 for vertical reciprocation is a solid piston 64. The piston 64 has an enlarged opening 66 extending longitudinally therethrough and receiving the drive pinion shaft 24, and that portion of the drive pinion shaft 24 disposed within the piston 64 is provided with a combination bearing spacer and cam wheel 68, the ends of the combination bearing spacer and cam wheel 68 engaging the bearing assemblies 20 and 22 and being positioned thereby.

It will be noted that the upper portion of the piston 64 is provided with a longitudinally extending rectangular cross-sectional slot 70 which communicates with the opening 66 and extends through the upper end of the piston. Mounted within the slot 70 for longitudinal movement therein is a T-shaped member 72 which has a stem portion 74 extending horizontally. The stem 74 is slidably mounted within a longitudinal bore 76 in that portion of the piston at the forward end of the slot. The T-shaped member 72 has a lower portion 78 which is adapted to engage the cam portion 80 of the combination bearing spacer and cam wheel 68 whereby the piston 64 may be reciprocated in response to rotation of the drive pinion shaft 24. It will be noted that the cam 80 of the bearing spacer and cam wheel 68 is of a nature whereby the piston 64 is reciprocated two complete strokes for each revolution of the drive pinion shaft 24. It will be understood that the T-shaped member may be selectively moved into or out of engagement with the cam 80 by control means which will be explained in more detail hereinafter, whereby the actuating pump assembly 56 may be selectively controlled by an operator of a vehicle to which the same is attached. Referring now to Figures 3 and 7 in particular, it will be seen that the differential gear case 28 has extending vertically through the central portion thereof a differential pump assembly, which is referred to in general by the reference numeral 82. The differential pump assembly 82 includes a cam 84 mounted on the differential pinion shaft 40, said cam 84 being adapted to engage inner ends of pistons 86 for reciprocating the same. The pistons 86 are mounted within cylinders 88 having cylinder heads 90 in the outer ends thereof. The cylinders 88 are connected at their inner ends by a generally circular cross sectional cam race 92 which is formed of an elastic steel. Extending transversely across the inner ends of the cylinders 88 are pins 94 which are received in transverse slots 96 in the lower ends of the pistons 86. The pistons 86 are also provided with longitudinally extending circular bores 98 in which are received coil springs 100 engaging the transverse pins 94 and urging the pistons 86 outwardly from the cam 84 and out of engagement therewith.

Referring now to Figure 3 in particular, it is seen that the differential carrier 12 is provided with a rearremoved.

wardly :extending afluid passage r102 which excommunimates with the ilower.:;endaof:.-the;cylinder-.58 \and provides bothan inlet; andsoutletafior ethe same. -Carried-;b.y,-.the

rear :endrof -:.the differential rcarrieri 12 nand :tdisposed ;in

,a SUIIIP"POItiQHS 104TQfZ the;differential-:reanaxle case 10 is a valve assembly, :WhiChiZlStfifeil'fidttolin general-thy the reference inumeral ,1 10.6. rIt will sbe-inotedrthat the valve assembly; incllldesna first (tubular portion s108ewhich is connected-atarightzranglesrtowa seeondtub'ular portion -110xtovformaaniLeshaped member. One wall of the tubularwportionr108.zis;of a relativelyczgreat thickness :and .;is provided 'twi'theank-internally :tthreaded wbore :1-12. The bore 1112 is aligned-Withtherfluid spassage 102-.and

..-an enlarged couter eend :thereof which .wis fr-interna'lly threaded as at 1114. :Threadedly engaged with the tinternally threaded :::bore .112 and the internally threaded portion .114 is 'anrexternally; threaded tconnecting .:member 116-having;ae:bore: 1 18 there'through whic'h:com-

:municates the fluid passage r102-4With.thenintetior .of the tubulariportion 108. Thewalve iassembly 1061s connected to the transversely extending portion .218 ;of..the differential carrier .12 :by-"the connecting :rnember 116 through the screwing $015 :the :nonnectingmember 116 into these .parts :through ether use rofnatsuitable stool (not shown) past throughzthe' valve-assembly e106- xwhen :parts thereof to be described in ;det-ail.=hereina;fter;have :been It will hes-understood 'thatif desired, :one; end .of the connecting member 116amay :be. provided'rwith a suitable tool engaging .zn'otchr to "facilitatersuch operation.

Thelower end:of 'the-iztubular aportion 5;;1-08 :of'ithe;

valve assembly f,-1'06;-':is':proyided :with ;an :inlet :opening .120 through "which 'gear :oil disposed 'lwithinvthe rear axle case 10 for lubricating the gears mounted ::therein is adapted to enter. Ullheiinlettopening'-120.in:thentubu- .lar portion -.108 is .nnorrnally -iclosed -;by -a 'eheck :valve 122 "which is urged to a;closed rpositionzzbysa coilspring .124. ,It will .be understoodrthat upon'mpward motion of :the piston 64 zoil will :be :drawn :throughtztheinlet .opening 120 into-the tubular portion :108n-and the :Lfluid :passage .102.

It will be notedrthat the forward :end of'thectubular portion 110 is provided with a: transverse wall 126, the

transverse wall ;.126 :being..disposed :within the .itubular portion 108. Thettransverset wall 1261is provided lwith ancoutlet opening 128 which is normally :closedrby a .pressure regulating-Halve 21130. :The cpressure :regulating -.valve ,130 is :urgefdnto a;;closed;,position-iby. a :coil1spring 132 mounted within rthez'tubularcportionl1:10wand. adjustably tensioned :bya rplug F134 adjustably threadedly engaged in therear endthereof. :It :will be understood that as therpiston :64 makesza downward stroke,--=oil=disposed within .the ffluidzpassage i102. and the upper part of the tubular portion 108: isurged throughthe outlet opening 128 and opens the ;pressure control walve 130.

Referring now toxFigure 7 .in particular, it is ;seen.;

38 is rigidly connected to the .dilferential carrier 12 and.

does not rotate with the differential bearing case .28. The lower end of the differential bearing cup -38 ;is .pro-

vided with aninternally threaded bore 144 which communicates with the fluid well 142 and has threadedly engaged therein on end of .apconnecting tube 146. The other end of the connecting tube 146 is flared and connected to the, externally threaded projecting, portion.136 of the valve assembly 106 'bya coupling .148 ,thre adedly engagedtthe're'on. .It' will be.understood-thatroil.pumped by the actuating pump-s assembly 56 v enters the fluid vwell :142 under pressure.

Theihalf'of the differential v gear-case 28,.inabutting relation with :the differential. bearing cup :38 is provided 'with a pair of longitudinally extending: fluid passages .150 ,which aresinalignmentwith thefiuid-well-142 and have roil'under pressure ..applied-thereto from-the fluid 4W6.

:The cylinders'88- are provided with aligned openings .152 and the cylinderheads 90tare provided.withealigned bores (154 whereby oilmay-be pumped therethrough. ,T-heother 'zhalf of the differentialgear 'case .28- is provided with a bore 156which is intalignment with the boresand open- .-ings.-150,u152 andzl54-whereby the same is providedrwith oil under pressure. .In..order.that oil tpumpednbyathe actuating pump assembly 1 56 may escape .in .small amounts, the outer ends. of the bores 156 are enlarged as at 158-and havemountedtherein pressureactuated valves .1160 which are urged to closed -positions by. coilrsprings -CO1'I11TlllnlCat6d.tOlhfiiDtfiIiOf-Ofihfi differential gear. case .128 by vent:passages--164. .It-will be understoodathatthe fluid actuated-valves .--160mormally .close the vent pas- 162. Therenlarged portions 158 of the bores 156 :are

sages 163 .and are;.opened by oil pressure from 'the eactuatingypump assembly .56.

'It will be noted that the cylinder heads '90.are provided by the actuating pump:assembly 56. The pressure tex- ,erted'upon the pistons-86 forces-the same inwardlyinto -engagement-with:the..cam-.84- and against the outward force of thecoil springs 100.

It willsbe :noted that the ditferential pinion-shaft =40 is providedwith azheavy metal core 166 in offset-relation .of the single'camr84. As-the vehicle,.-in -which the rearaxle assembly describedherein- .aboveis assembled, travels along a road. at low speed and makesa turn or has one wheel thereof in slipping engagement with-the road whereby one of the axles 52 has a tendencyto turn with respect .to the other, the-rotation of the differential-pinion '44, which .is :integral with differential pinionshaft 40-is resisted-due-tothe relative immobility of thepistons 86, Inasmuch as the pistons 86 are prevented from reciprocating, .the cam -84 is prevented from rotating and likewise the diflerentialzpinion shaft 40 is also; prevented from rotating. It will, therefore, be seen that when =the actuating pump assembly 56 .is engagedthat the-,difierential .action -.between the axles 52 has .beemprevented .and that the two .axles v are substantially connected together-as a .unit.

.It is recognized tthat-iwhen the :hydraulic vdiflferential control mechanism, -which 'is thesubject .of .this .invention, operates .toulock theaaxles 52 .togethertas 71a driving unit, that there-are :certain vehicular operatingtconditions .which .might suddenly:;;pla.ce .the entire torque of the vehicle-s motor ;on..- one .of the .driven \wheels rand-its associated axles-52. :Suoh. an operatingcondition :might occur --when, sdue rto road sconditions, :one driven T wheel becomes, momentarily iandtfor ean appreciable .ilength -0f time, free of the roadssurf-ace. 'Anotheroperating-position which might'place "the entire-torque ofthe'vehicles motor on one-driven wheebwouldoccur in-"th'e event" of a sudden tire 'failure, such asalblow-out. sIfeither'offthe above-mentioned operating conditions occurred while the ihydraulic'diflerential control mechanismwas in the.act of regulating diflerentialaction, there would be,. of course, a sudden increase of differential motion .that would prevcede a greater rate of speed than could be permittedby the difierential control mechanism. Since .this increased differential motion would have to occur if .thevehicle were operated safety, suchvmotion would tear asunderthe differential pump assembly and thereby permanently .ruin the vital parts of the. vehicles rear .axle assembly. .iIf the differential pump assembly, which is. 'referred to. ingeneral by the reference numeral 82, were not torn asunder,

the vehicle could not be operated safely.

It will be noted that in the description of the generally circular cam race 92 which connects together the cylinders 88 that the same was described as being formed of a spring steel. When the differential action results in the sudden rotation of the differential pinion shaft 40, the

- pistons 86 will be rapidly reciprocated with the result that fluid could not be pumped out of the bores 164 sufficier-tly fast to permit outward movement of the pistons 86. Therefore, there woud be a tendency to either force the cylinder heads 90 out of their respective cylinders 88 or to tear apart the differential gear mechanism. However, since the cam race 92 is formed of an elastic steel, the cylinder heads 90 are urged apart with the resultant movement of the associated cylinders 88 away from each other and the flattening of the generally curved cam race 92 to an elliptical shape, such as illustrated in Figure 8. It will be noted that the bores 150 and 156 of the halves of the differential gear case 28 are provided with outwardly open bores 168 and 170, respectively. When the cylinders 88 are in their normal positions, annular flanges 172 on the outer ends thereof are in engagement with the outer surface of the differential gear case 28 and close the openings 168 and 170. When the cylinders 88 are in their outwardly urged positions, the openings 152 therethrough are aligned with the openings 168 and 170 whereby oil pumped by the pistons 86 is permitted to escape into the rear axle case along with oil pumped by the actuating pump assembly 56.

Referring now to Figure 7 in particular, it will be seen that the upper end of the differential bearing cup 38 is provided with an internally threaded bore 174 in which is threadedly engaged one end of one arm of the T-shaped fitting 176. The other arm of T-shaped fitting 176 is externally threaded and provided with a closure cap 178. It will be noted that the arm that is closed by the closure cap 178 is partially closed from the remaining portion of the T-shaped fitting 176 by a transverse wall 180 having a small opening 182 therethrough. It is intended that the said other arm form an air dome 184 in which air is adapted to be disposed and compressed by fluid pumped by the actuating pump assembly 56 and passing through the T-shaped fitting 176. The purpose of the air dome 184 is to maintain a steady pressure within the fluid well 142 in spite of the pulsation movement of the actuating pump assembly 56.

Referring now to Figure 3 in particular, it will be seen that connected to the stem of the T-shaped fitting 176 is a pressure regulating pipe 186 for instantaneously disengaging the ditferential pump assembly 82 from the actuating pump assembly 56. The forward end of the pressure regulating pipe 186 passes through a bore 188 in the transverse portion 18 of the differential carrier 12 and is positioned with respect thereto by an intermediate annular shoulder 190 which engages the rear surface of the transverse portion 18. The extreme forward end of the pressure regulating pipe 186 passes through a bore 192 in the transverse portion 16 and is provided with an externally threaded end portion 194. Threadedly engaged on the end portion 194 is a connecting member 196 which retains the pressure regulating pipe 186 in place. That portion of the pressure regulating pipe 186 disposed within the cylinder 58 of the actuating pump assembly 56 is provided with a transverse bulkhead 198 closing the end thereof and preventing flow of fluid through the remaining portion of the pressure regulating pipe. The side wall of the pressure regulating pipe 186 is provided with a fluid outlet opening 200 adjacent the bulkhead 198 through which oil may escape.

Carried by the portion of the pressure regulating pipe 186 forward of the bulkhead 198 is a rod 2&2 which has secured to a rear end portion thereof a vertically ex tending pin 204. The vertically extending pin 284 extends through longitudinally extending slots 206 in the pressure regulating pipe 186 and is connected to a valve sleeve 208 slidably mounted on the forward end of the pressure regulating pipe 186. The lower end of the vertical pin 204 is threadedly engaged in the T-shaped member 72 and is utilized for moving the same longitudinally with respect to the drive pinion shaft 24.

Connected to the forward end of the rod 202 is a flexible cable 210 which is mounted in a flexible housing 212, the flexible housing 212 being secured to the forward end of the connecting member 196. Disposed within the connecting member 196 is a coil spring 214 which engages the forward end of the rod 202 and urges the same rearwardly to a position whereby the rear end thereof engages the bulkhead 198. It will be understood that when the rod 202 is in its rearmost position, the T-shaped member 72 is out of engagement with the cam 80 and the actuating pump assembly 56 is not operatively connected to the drive pinion shaft 24. At this time a rectangular opening 216 in the sleeve 208 is aligned with the outlet opening 200 to permit oil within the pressure regulating pipe 186 to escape.

As is best illustrated in Figure 6, the closure plate of the cylinder 58 is provided with a pair of downwardly extending projections 218 which are disposed on opposite sides of the pressure regulating pipe 186 and in alignment with circular recesses 220 in the upper surface of the piston 64. Extending between the piston 64 and the closure plate 60 is a pair of coil springs 222 whose upper ends are disposed around the projections 218 and whose lower ends are disposed within the recesses 220. It will be understood that the coil springs 222 urge the piston 64 downwardly against the upward movement of the cam 68.

Referring now to Figures 1 and 2 in particular, it will be seen that there is illustrated a floor board of a vehicle in which the rear axle case 10 is mounted. The floor board is referred to in general by the reference numeral 224 and has pivotally connected thereto by a connection 226 an accelerator pedal 228. The accelerator pedal 228 has connected thereto a carburetor control rod 230 which passes through an opening 232 in the floor board 224.

Disposed forwardly of the accelerator pedal 228 and secured to the underside of the floor board 224 is a fitting, which is referred to in general by reference numeral 234. The fitting '234 has a rearwardly extending internally threaded bore 236 in which is threadedly engaged the forward end of the housing for the flexible cable 210. The flexible cable 210 extends through the fitting 234 and is clamped therein by a set screw 238 in an end of the fitting 234 opposite from the connection to the housing 212. Extending transversely of the flexible cable 210 and opening upwardly is an enlarged bore 240 through which the flexible cable 210 passes.

The floor board 224 is provided with a bore 242 in alignment with'the opening 240 and through which passes a reduced lower end 244 of an actuating rod 246.

Carried by a supporting plate 248 is an upper bearing 250 which is in alignment with the bore 242 and supports the upper end of the control rod 246 and limits the up ward movement thereof. It will be noted that the control rod 246 has the reduced lower end thereof in engagement with the flexible cable 210 and is urged upwardly by a coil spring 252, carried by the reduced end portion 244.

Surrounding the control rod 246 is an elongated tubular collar 254 which has connected to the upper end portion thereof a leaf spring 256. The leaf spring has conneeted to its upper end a finger anchor 258 which is provided with an inwardly extending recess 260. The recess 260 is adapted to receive a projecting portion of a pin 262 carried by the control rod 246 to connect the finger anchor 25% thereto. It will be understood that the finger anchor 258 may be disconnected from the anchor pin 262 by pulling the same rearwardly and away from the control rod 246 and then permitting the same to be lowered.

emen-a4 -side flanges"266 is a connecting pin,268about .which is looped an intermediate .portion of a springxarm'2'l0. 'The :spring arm 270 underlies the forward end of the:accelerator pedal 228and-is-engaged thereby and-:moves thecollar "254 androd'246 whenvconnected to the control rod 246.

-'Downward movement of the accelerator pedal 228 will result in the downward movement of thespring arm 270 -.and the resultant movement of the collari254 :and .the control rod 246. *Downward movement of the control -.r0 d 246 results iin'theiben'dingsof ithe'flexible cable 210 with the resultantiforward pulling of the rear end thereof soas to move the :rod 202 forward from the position illustrated in Figure 4 andactuate the sleeve valve 208 and the I -shaped member 72 whereby 'theractuating pump passembly56 isactuated. Accordingly, it will be readily apparent ithat the control mechanism .for the fluid govlernor is operatively connected :to the accelerator pedal ;t228 for control thereby. While the:control :rod'246 and :thecollar1254 have only limited downward movement, it rwill be noted'that the accelerator pedal 224 may be con- "tinued to be pressed'down even'ithoughlthe downward movement of the collar'254shas'been stopped due to: the

' 'by:the springs 100 is greaterthanthe pressure exerted on the :pistons by :.'the oil pump -by the actuating pump assembly-'56 so that the pistonsare not urged into engage ment with :the cam 8'4and therefore, the hydraulic differeential control mechanism, which zis' the subject of this :invention, is automaticallydisengaged-upon the reaching -tof alspeed :in excess of 15- miles per-hour by the .vehicle.

Due to this novel arrangement, =it- -will"be seen that, if it 'isdesired, the actuating means for the hydraulic differenitial control mechanism may be retained in -engagement with-the accelerator pedal ZEZ'S at all timesyif it' is sode- -sired,:providing the operator of the-vehicledesires tohave the differential action regulated at low speeds. It will be understood that the primary in'tention'ofthis'invention is-to provide means'for lockingthe differential action of a vehicle at low speed whereby the same-maybe 2 controlled on slippery roads, or in the case of-country roads, -or-muddy roads. 'It-will be'understood that the speed at--which the regulatingof'thedifferential action is continued may be variedby-adjusting the plug '134 in the valve assembly-106 to adjust the tension of the coil spring'132.

The operation of this device will be -.understood from the foregoing description of the ,detailsthereof, taken in connection with the above recited objects and drawings. a 60 'Furtherdescription would appearzto be unnecessary.

"Minor modifications of the device,- varying in-iminor details fro1n;the embodiment.ofthedevice :illustrated and described. here, may be rresorted :to without departure from :the spirit and scop of .this. invention, :as; defined. in I ;,the, appended .claims.

t-Having described the invention, what; is tclaimedzasnew ..l. {A wfluid governor-for controlling differential; action of a idrive \axle differential having a drive pinion fshaft 7 and ,a differential pinionz shaft having, a fixed-differential ,pinion secured :thereto,.- axle pinionscngaged-with said :differential z pinion "for rotating -;said differential pinion shaft [and responsive toqopposite -.irotation of -said axle minions, wsaidrrfluidg governor including. agfirst'cfluid :pump

:driven hyalsaididrive pinion.shaftptalsecond'fluid pump driven by'said-differential :pinion shaft, 'p'iperneans. inter- .communicating :saidyflrst anclzsecond fluid pumps :inyop- -posed relationtwhereby fluidpumped ;by said firstvfluid ..purnp resistsiactuation of .said second .fluid :pump to-;pro- 1 .vide .-ai-:-braking zZlCflOIl on said differential pinion shaft.

.2. iA' fluidngovernor for controlling differential having ..:a2drive pinion shaftanda-differential:pinion shaft having a fixed differential pinion secured thereto, axle pinions engaged with said zdifferential pinion forsrotatingsaid idifferential pinion shaftandresponsive to oppositerotation-.of-said axle pinions, said fluid governor including a "firstfluid-pump driven by-said drive pinionshaft, asecond fluid pump driven by said differential pinion shaft, .pipe means inter-communicating .said first and second .fluid pumps in opposted relation wherebyfluid pumped by said first fluid pump resistsactuation of said second ifluidpurnp to provide.a.braking action on said differential .pinion shaft, said second fluid pump including cylinders having pistons reciprocably mounted therein, said cylinders being mounted within a differential gear case for said :differentialpinions and being artially movable out ofsaid gear case, said cylinders :beingmovable in response :to, overridingofsaidbraking actionto permit said pistons tov rotate.

3. A1fluid governor for controlling differential action iofwia drive axle'differen'tial having a drive pinion shaft 3111113 differential'pinion shaft having'a fixed differential pinion secured thereto, axle pinions engaged with said differential pinion vfor rotating said differential pinion shaft and responsive to opposite rotation of said axle ,pinions, said fluid governor including a first fluid pump .driven by said drive pinion shaft, a second fluid pump fldrivenby said differential pinion shaft, pipe means intercommunicating said first and second fluid pumps in opposed :relation whereby=ifluid :pumped by said first fluid -:pump xresists-actuationof said second fluid pump to pro- :vide a bral zingactio-n on said differential pinion shaft, said first. fluid pump including acam :mounted on saiddrive :pi-n'ion shaft, aiconnecting member carried by a piston of said first pump selectively engageable with said cam for ereciprocating said-piston.

A. A fluidgovernor for controlling differential action sofa drive axle differential havinga drive pinion shaft and naedifferential ,pinion shaft having a'fixed' differential pin- :ionzsecured thereto,-axle-pinions engaged with said differiential pinion for-rotating said differential pinion shaft and tresponsive to opposite rotation of said axle pinions, said fluid :governor includinga first fluid pump driven by said .rdrive=pinion'shaft, a :second fluidpump driven by said dif- 'gferential pinio-nshaft, pipe means inter-communicating said flrst' andsecond fluid pumps in opposed relation whereby :fluid-pumped-by said first fluid pump resists actuation of .said second fluid pump to provide'a braking action on v said differential pinion shaft, said'first fluid pump includaingwa cam mounted on'said drivepinion shaft, a connect- :ing'member carriedbya piston of said first-pump selectively engageable with said cam for reciprocating said piston, said-connecting member-being shiftable by conv:trol -.means selectively operable by an operator of a ve- =-hicle=so equippedgfor selectively operating said first fluid pump.

' '55. A fluid governor forcontrolling differential action .of a 'drive axle differential having "a drive pinionshaft .and a:'differential .pinion' shaft having a fixed difierential pinion secured thereto, axle pinions engaged withv said differential pinion for rotating said differential pinion -;shaft and-responsive to opposite rotation of said axle pinions, said fluid governor including a first fluid pump .r'drivenaby'zsaid drive pinionshaft, a second fluid pump driven by said differential pinion'shaft, pipe meansintercommunicating saidfirst and second fluid pumps in op- :posedrelation whereby fluid pumped'by said first fluid lpumpxresists actuation of said second fluid pump to prowidewartbraking ;action on said-differential pinion shaft,

said first fluid pump including a cam mounted on said drive pinion shaft, a connecting member carried by a piston of said first pump selectively engageable with said cam for reciprocating said piston, said connecting member being shiftable by control means selectively operable by an operator of a vehicle so equipped for selectively operating said first fluid pump, said control means being provided with a connection to selectively render the same operative.

6. A fluid governor for controlling differential action of a drive axle differential having a drive pinion shaft and a differential pinion shaft having a fixed differential pinion secured thereto, axle pinions engaged with said differential pinion for rotating said differential pinion shaft and responsive to opposite rotation of said axle pinions, said fluid governor including a first fluid pump driven by said driven pinion shaft, 21 second fluid pump driven by said differential pinion shaft, pipe means intercommunicating said first and second fluid pumps in opposed relation whereby fiuid pumped by said first fluid pump resists actuation of said second fluid pump to provide a braking action on said differential pinion shaft, said fluid pumps pumping gear oil used for lubricating drive and differential gears in a drive axle assembly, said gear oil being disposed within a drive axle gear housing.

7. A fluid governor for controlling differential action of a drive axle differential having a drive pinion shaft and a differential pinion shaft having a fixed differential pinion secured thereto, axle pinions engaged with said differential pinion for rotating said differential pinion shaft and responsive to opposite rotation of said axle pinions, said fluid governor including a first fluid pump driven by said drive pinion shaft, a second fluid pump driven by said differential pinion shaft, pipe means intercornmunicating said first and second fluid pumps in opposed relation whereby flttid pumped by said first fluid pump resists actuation of said second fluid pump to provide a braking action on said differential pinion shaft, said means being in the form of a fluid line, a fluid intake carried by said fluid line for permitting intake only of fluid from a drive axle gear case.

8. A fluid governor for controlling differential action of a drive axle differential having a drive pinion shaft and a differential pinion shaft having a fixed differential pinion secured thereto, axle pinions engaged with said differential pinion for rotating said differential pinion shaft and responsive to opposite rotation of said axle pinions, said fluid governor including a first fluid pump driven by said drive pinion shaft, a second fluid pump driven by said differential pinion shaft, pipe means intercommunicating said first and second fluid pumps in opposed relation whereby fluid pumped by said first fluid pump resists actuation of said second fluid pump to provide a braking action on said differential pinion shaft, said second fluid pump including pistons driven by a cam mounted on said differential pinion shaft, said pistons being normally urged out of engagement with said cam by spring elements.

9. A fluid governor for controlling differential action of a drive axle differential having a drive pinion shaft and a differential pinion shaft having a fixed differential pinion secured thereto, axle pinions engaged with said differential pinion for rotating said differential pinion shaft and responsive to opposite rotation of said axle pinions, said fluid governor including a first fluid pump driven by said drive pinion shaft, a second fluid pump driven by said differential pinion shaft, pipe means intercommunicating said first and second fluid pumps in opposed relation whereby fluid pumped by said first fluid purnp resists actuation of said second fluid pump to provide a braking action on said differential pinion shaft, said second fluid pump including pistons driven by a cam mounted on said differential pinion shaft, said pistons being normally urged out of engagement with said cam by spring elements, fluid inlets for said pistons being con- 12 nected to said first fluid pump whereby said pistons are urged into engagement with said cam.

10. A fluid governor for controlling differential action of a drive axle differential having a drive pinion shaft and a differential pinion shaft having a fixed differential pinion secured thereto, axle pinions engaged with said differential pinion for rotating said differential pinion shaft and responsive to opposite rotation of said axle pinions, said fluid governor including a first fluid pump driven by said drive pinion shaft, a second fluid pump driven by said differential pinion shaft, pipe means intercommunicating said first and second fluid pumps in opposed relation whereby fluid pumped by said first fluid pump resists actuation of said second fluid pump to provide a braking action on said differential pinion shaft, said second fluid pump including pistons driven by a cam mounted on said differential pinion shaft, said pistons being normally urged out of engagement with said cam by spring elements, fluid inlets for said pistons being connected to said first fluid pump whereby said pistons are urged into engagement with said cam, the force exerted on said pistons by said first fluid pump being less than the combined force of said spring elements plus centrifugal force on said piston at higher axle speeds.

11. A fluid governor for controlling differential action of a drive axle differential having a drive pinion shaft and a differential pinion shaft having a fixed differential pinion secured thereto, axle pinions engaged with said differential pinion for rotating said differential pinion shaft and responsive to opposite rotation of said axle pinions, said fluid governor including a first fluid pump driven by said drive pinion shaft, a second fluid pump driven by said differential pinion shaft, pipe means inter-communicating said first and second fluid pumps in opposed relation whereby fluid pumped by said first fluid pump resists actuation of said second fluid pump to provide a braking action on said differential pinion shaft, said drive axle differential also including a differential carrier and a diflerent bearing cap, said means being in the form of fluid passages formed in said differential bearing cap rigidly connected to said differential carrier in which said drive pinion shaft is mounted.

12. A fluid governor for controlling differential action of a drive axle differential having a drive pinion shaft and a differential pinion shaft having a fixed differential pinion secured thereto, axle pinions engaged with said differential pinion for rotating said differential pinion shaft and responsive to opposite rotation of said axle pinions, said fluid governor including a first fluid pump driven by said drive pinion shaft, a second fluid pump driven by said differential pinion shaft, pipe means intercommunicating said first and second fluid pumps in opposed relation whereby fluid pumped by said first fluid pump resists actuation of said second fluid pump to provide a braking action on said differential pinion shaft, said drive axle differential also including a differential carrier and a differential bearing cap, said means being in the form of fluid passages formed in said differential bear ing cap rigidly connected to said differential carrier in which said drive pinion shaft is mounted, said fluid passages including an air dome for stabilizing fluid pressure within said fluid passages.

13. A fluid governor for controlling differential action of a drive axle differential having a drive pinion shaft and a differential pinion shaft having a fixed differential pinion secured thereto, axle pinions engaged with said differential pinion for rotating said differential pinion shaft and responsive to opposite rotation of said axle pinions, said fluid governor including a first fluid pump driven by said drive pinion shaft, a second fluid pump driven by said differential pinion shaft, pipe means intercommunicating said first and second fluid pumps in opposed relation whereby fluid pumped by said first fluid pump resists actuation of said second fluid pump to provide a braking action on said differential pinion shaft,

13 said second fluid pump including a pair of opposed cylinders connected by a circular central portion, said central portion being formed of spring metal whereby said cylinders may move apart when movement of pistons in said cylinders is restrained.

14. The fluid governor of claim 1 wherein said first pump is provided with control means for selectively engaging said first pump with said drive pinion shaft, said control means being operatively connected to an accelerator pedal of an associated vehicle.

15. The fluid governor of claim 1 wherein said first pump is provided with control means for selectively engaging said first pump with said drive pinion shaft, said control means being operatively connected to an accelerator pedal of an associated vehicle, said control means being provided with a connection to selectively render the same inoperative.

16. The fluid governor of claim 1 wherein said first pump is provided with control means for selectively engaging said first pump with said drive pinion shaft, said control means being operatively connected to an accelerator pedal of an associated vehicle, said first pump having an inlet valve, said control means actuating said inlet valve when operated.

References Cited in the file of this patent UNITED STATES PATENTS 1,178,093 Moon Apr. 4, 1916 1,374,603 Patten Apr. 12, 1921 1,479,752 Smith Jan. 1, 1924 1,646,020 Fottinger Oct. 18, 1927 1,659,833 Norrlin Feb. 21, 1928 1,683,938 Wildhaber Sept. 11, 1928 1,918,025 Frankford July 11, 1932 1,919,930 Cash July 25, 1933 2,004,929 Centervall June 18, 1935 2,312,274 Stortz Feb. 23, 1943 2,375,938 Moon May 15, 1945 2,452,981 Benning Nov. 2, 1948 2,532,757 Butterworth Dec. 5, 1950 

